Array

Scala provides a data structure, the array, which stores a fixed-size sequential collection of elements of the same type. An array is used to store a collection of data, but it is often more useful to think of an array as a collection of variables of the same type. The index of first element of an array is zero and the last element is the total number of elements minus one.

There are a few different ways to create String arrays in Scala. If you know all your array elements initially, you can create a Scala string array like this:

val fruits = Array("Apple", "Banana", "Orange")

If you don't know the strings that you want in your array initially, but know the size of your array, you can create it first, then populate it later, like this:

val fruits = new Array[String](3)

val number = new Array[Int](3)

// somewhere later in the code ...

fruits(0) = "Apple"

fruits(1) = "Banana"

fruits(2) = "Orange"

//

fruits.update(0,"Apple")

fruits.update(1,"Banana")

fruits.update(2,"Orange")

Example1

object Array1 {
  def main(args :Array[String])
  {
    var days = Array("Sunday", "Monday", "Tuesday","Wednesday", "Thursday", "Friday","Saturday" )
    println("Array elements are : ")
    for ( i <-days )
    {
      println(i)
    }
  }
}

Example2

object Array2 {
  def main(args :Array[String])
  {
    var days = new Array[String](7)
    days(0)="Sunday"
    days(1)="Monday"
    days(2)="Tuesday"
    days(3)="Wednesday"
    days(4)="Thursday"
    days(5)="Friday"
    days(6)="Saturday"
    println("Array elements are : ")
    for ( i <-days )
    {
      println(i)
    }
  }
}

Update the elements of the arrays

object Array3 {
  def main(args :Array[String])
  {
    var days = Array("Sunday", "Monday", "Tuesday","Wednesday", "Thursday", "Friday","Saturday" )
    days(1)="Friday"
    println("After update array elements are : ")
    for ( i <- days )
    {
      println(i)
    }
  }
}

Mutable Scala String arrays

Note that if you want to create a mutable Scala String array, you really want to use the Scala ArrayBuffer class instead of the Array class, like this:

import scala.collection.mutable.ArrayBuffer
object MainObject {
  def main(args: Array[String]) {
    var fruits = ArrayBuffer[String]()
    fruits += "Apple"
    fruits += "Banana"
    fruits += "Orange"
    print("Array Elements are:  \n")
    for(i <- fruits)
      {
        print(i)
        print("\n")
      }
  }
}

Example4

import scala.collection.mutable.ArrayBuffer
object test{
  def main(args: Array[String])
  {
    var str = ArrayBuffer [String]()
    str += "Hi"
    str +="Hello"
    str +="How are you"
    str -="Hi"
    println(str)
  }
}

Example5

Delete elements for the ArrayBuffer.

We can delete array elements using .remove and -.

import scala.collection.mutable.ArrayBuffer
object demo {
  def main(args : Array[String]){
    var str = ArrayBuffer [String]()
    str += "Hi"
    str +="Hello"
    str +="How are you"
    str.append("Welcome")
    str -="Hi"
    str.remove(2)
    println(str)
  }
}

Append elements to an  arrays

•  :+  append one item to existing Array
• ++ append many items to existing Array
• +:  prepend 1 item to existing Array
• ++: prepend many items to existing Array

How to merge  Array

object demo {
  def main(args : Array[String]){
    val a = Array(1,2,3,4,5)
    val b = Array(4,5,6,7,8)
    val c= a++b
    for ( i <- c) {
      print(i)
    }
    println("\n")
    val d=Array.concat(a, b)
    for ( i <- d) {
      print(i)
    }
  }
}

Concat elements to an  arrays

import Array._
object Demo {
  def main(args: Array[String]) {
    var sname = Array("John","Adam","Rob","Reena","Harry")
    var sname1 = Array("Jack","Jill","Henry","Mary","Rohan")

    var names =  concat( sname, sname1)
    println("Student name array elements are  : ");
    for ( n1 <- names ) {
      println( n1 )
    }
  }
}

Intersect of array elements

object Demo {
  def main(args: Array[String]) {
    var sname = Array("John","Adam","Rob","Reena","Harry")
    var sname1 = Array("Jack","Jill","Henry","John","Mary","Rohan")
    var names = sname.intersect(sname1)
    println("Student name array elements are  : ");
    for ( n1 <- names ) {
      println( n1 )
    }
  }
}

Union of array elements

import Array._
object Demo {
    def main(args: Array[String]) {
      var sname = Array("John","Adam","Rob","Reena","Harry")
      var sname1 = Array("Jack","Jill","Henry","John","Mary","Rohan")
      var names = sname.union (sname1)
      println("Student name array elements are  : ");
      for ( n1 <- names ) {
        println( n1 )
      }
    }
  }

Array With Range

import Array._
object Demo {
  def main(args: Array[String]) {
    var id = range(7, 23, 3)
    var age = range(15,20)
    for ( s <- id ) {
      print( " " + s)
    }
    println()
    for ( a <- age ) {
      print( " " + a )
    }
  }
}

Multidimensional Array in Scala

To create a multi-dimensional array in Scala, in this case a 2D array (matrix), and then access the array elements.

ofDim method is used for multidimensional query.

object demo
{
  def main(args:Array[String]) {
    val rows = 2
    val cols= 3
    val a = Array.ofDim[String](rows, cols)
    a(0)(0) = "a"
    a(0)(1) = "b"
    a(0)(2) = "c"
    a(1)(0) = "d"
    a(1)(1) = "e"
    a(1)(2) = "f"
    for{
      i <- 0 until rows
      j <- 0 until cols
    }
      println(s"($i)($j) = ${a(i)(j)}")
  }
}

// distinct elements from both collections
scala> val c = a.union(b).distinct
c: Array[Int] = Array(1, 2, 3, 4, 5, 6, 7, 8)

scala> val c = a diff b
c: Array[Int] = Array(1, 2, 3)

scala> val c = b diff a
c: Array[Int] = Array(6, 7, 8)

What Are The Differences Between Array And Arraybuffer In Scala?

Differences between Array and ArrayBuffer in Scala:
 Array is fixed size array. We cannot change its size once its created.
 ArrayBuffer is variable size array. It can increase or decrease it’s size dynamically.
 Array is something similar to Java’s primitive arrays.
 ArrayBuffer is something similar to Java’s ArrayList.